Temperature responsive control switch with bi-metallic disk means

ABSTRACT

A temperature-compensated gas density relay includes a bellows unit subjected to the gas, the pressure from which is transmitted by the bellows unit through a support mounting a bi-metallic disc and a shaft carried by the central portion of the bi-metallic, and longitudinal displacement of the shaft in response to the change in gas pressure serves to actuate the contacts of an electrical switch component of the relay. Should there be a change in the gas temperature, compensation therefor is accomplished by a temperature-induced displacement of the central portion of the bi-metallic disc, and hence also the shaft, in a direction opposite to that caused by the change in the gas pressure resulting from that same change in temperature.

States Patent 1191 Kalt et al. 14 1 July 1 .1973

541 TEMPERATURE RESPONSIVE coNTRoL 3,412,357 11/1968 Odashima 337/307SWITCH WITH Ill-METALLIC DISK MEANS. 3,619,526

[75] Inventors: Ulrich Kalt, Lauffohr; Rolf Kiing, Prima ryExammer-Herman J. Hohauser Nussbaumen both of Sw'tzerland AssistantExaminer-Gerald P. Tolin [73] Assignee: Aktiengesellschaft Brown, Boveri& A rn y-Ralph P e e Cie, Baden, Switzerland 221 Filed: Dec. 21, 1971[571 ABSTRACT 1 1 A temperature'compensated gas density relay includesAppl' 210526 a bellows unit subjected to the gas, the pressure fromwhich is transmitted by the bellows unit through a sup- [30] ForeignApplication Priority Data port mounting a bi-metallic disc and a shaftcarried by Feb. 24, 1971 Switzerland 2640/71 the central Portion of thebimetallic, and longitudinal displacement of the shaft in response tothe change in 52 0s. (:1. 200/83 R, 337/319 gas Preswre serves toactuate the contacts Ofan electri- 51 Int. Cl. 11011135/32 cal Switchcomponent of the y- Should be a 581 Field of Search 200/83 A, 83 c, 83w, change in the gas temperature, compensation therefdr 200/83 P, 166 M;337/307, 308,319 is accomplished by a temperature-induced displacementof the central portion of the bi-metallic disc, and 5 References Citedhence also the shaft, in a direction opposite to that UNITED STATESPATENTS causedby the change in the gas pressure resulting from that samechange in temperature. 3,129,309 4/1964 McKeough ZOO/8L5 3,490,342[/1970 Reis 200/83 W 4 Claims, 1 Drawing Figure a 6 67 wt 5 v 1. 2

ll/l97l Riley 200/166 M TEMPERATURE RESPONSIVE CONTROL SWITCH WITHBl-METALLIC DISK MEANS Y This invention is directed to an improvement inthe construction of a temperature-compensated gas density relay andwherein an element responding both to'pres sure and to temperature ofthe gas act in opposite directions on the operating element for anelectrical switch component of the relay.

Such gas-density relays are used, for example, in gas circulatingswitches of the closed gas circuit type which are operated preferablywith sulphur hexachloride sure within the nipple changes,the length ofthe bellows unit 3 will also change and hence the support member 4 willgo up or down dependent upon the sense of the change in pressure. Thecircular head portion of the support member 4 has secured to it the rimof a bimetallic temperature compensating disc 5 and the latter isprovided with a central opening and through which the lower portion of ashaft 6 extends slidably into the hollow stem portion of the support 4for guiding the shaft. An intermediate collar 6a on shaft 6 abuts and issecured to the upper face of the bimetallic disc (SP that serves both asa quenching gas for arc extinction and also as an insulation gas for theswitch parts at responsive element actsagainst atemperature compensatinga back-pressure created by a fluid substance in a sensor responsive tochanges in temperature. However, the fastening and adjustment'of theheat sensor are still relatively complicated and also expensive. I

The objective of the present invention is to provide a more simple andinexpensive solution for compensating temperature changes in a gasdensity relay. The ob- 5 at the pass-through point of the shaft. Henceas the bellows unit 3 contracts or expands longitudinally in "accordancewith a change in gas pressure', the corresponding longitudinal movementof the stem portion of the support 4 will be transmitted through thebimetallic disc 5 and collar 6a to shaft 6.

a The upper portion of shaft 6 passes through an opening in anintermediate plate which latter serves to close off the space withinwhich the support member 4 operates and the upper end of the shaftterminates within a chambered'part of the housing structure in which onejective is attained in'that a shaft com'ponent'of the relay utilized foractuating contacts of the electrical switch included in the relay issecured to the center of a bimetallic disc responsive to a change intemperature,v

this disc being secured at its periphery to a support member which inturn issecured to one end of a bellows unit subjected to the pressure ofthe gas being supervised. Should a change in gas temperature occur whichwould tend to actuate the assembly of the bellows unit, support memberand contact-actuating shaft in one direction, the central portion of thebi-metallic disc and the shaft will be displaced by a correspondingamount in the opposite direction relative to the support member, thusnullifying the effect of the temperature change.

The foregoing as well as other objects and advantages inherent in theinvention will become'more apparent from the following detaileddescription of one suitable embodiment of the invention and from theaccompanying drawing wherein the single view presented is a cenadaptedto be screwed onto the end of a pipe or container containing the gaswhose pressure is to'be supervised. The nipple l is rigidly connected tothe lower part of a housing 2 by means of a plurality of fastening boltsone of which is shown, and the-upper part of the nipple terminates in anend wall provided with an opening and around which one end of a bellowsunit 3 is secured within the nipple by soldering. The hollow stemportion of a mushroom-shaped supporting member 4, which operates withinthe housing part 2, extends through the opening in the end of the nipple1 and interiorly through the bellows unit 3 to the bottom of the latter,the arrangement beingsuch that as the gas presor more micro switches 9are mounted for pivotal movement by means of a pivot shaft 12. A spring11 of the double leaf type provided for each micro switch includes acentral loop around the pivot shaft 12, a first laterally-extending leafportion having its end in abutment with a lug 10 on the casing of themicro switch 9, and a second donwwardly extending leaf portion .whichbears against an abutment established by a pivot shaft 8 which mounts alever! that is operated by the end of shaft 6 Lever 7 in turn, actuatesa plunger 9a for each micro switch controlling the contacts of thelatter v v Spring 11 biases the micro switch 9 a counterclockwisedirection about the pivot shaft 12 so as to abut against the upper endof an adjustment screw 13 by means of which the distance between theplunger 90 and its contact with the upper side of lever 7' can beadjusted thus-effecting a corresponding adjustment in the workingpoint-of the switchcontacts in relation to the pressure condition of thegas. 7

when removed provides access to a terminal strip 14 to I whichconnecting conductors are led from theright to the micro switches 9, andalso access to a stuffing box 16 secured to a side wall of the housingthrough which the external conductors can be led into the housing andfastened to terminal strip 14.

As has been explained, as the pressure of the gas within nipple 1 beingsupervised changes, e.g., fincreases, bellows 6 will be pushed up andshortened, this movement being transmitted by 'way of the support member4 and bi-metallic disc 5 to shaft 6 thus displac ing the latter upwardto actuate lever 7 which turn pressesagainst and actuates the plunger ofthe micro-switch 9 so that the switch contacts open'and hence cutoff thegas compressor. Conversely, should the gas density and hence itspressure decrease, the component parts will move in the oppositedirection thus releasing tion of the support 4. Thus for example, shouldthere be an increase in gas temperature which would be reflected in acorresponding increase in its pressure tend- I 1. In atemperature-compensated gas density relay the combination comprising abellows unit subjectable to a pressurized gas to be supervised, one endof said bellows unit being fixed in position and the other end which ismovable in response to a' change in gas pressure being secured to asupport member to effect a corresponding movement thereof in a directionlongitudinally of the bellows unit, a temperature-compensatingbi-metallic disc subjectable to the temperature of the gas and havingonly the peripheral portion thereof secured to said support member formovement therewith, and a relay operating shaft secured to the centralportion of said bi-metallic disc which is moved in one direction toactuate a relay member such as the contacts of an electrical switch inresponse to movement of said bellows unit effected by an increase in gaspressure, said central portion of said bi-metallic disc being spacedfrom said support member and said central portion together with saidrelay operating shaft secured thereto being movable in the oppositedirectionupon an increase in gas temperature thereby to compensate foran increase in gas pressure resulting solely from an increase in itstemperature.

2. A temperature compensated gas density relay as defined in'claim 5wherein said support member includes a head portion to which theperiphery of said bimetallic disc is secured and a hollow stem portioninto which a portion of said shaft extends and is guided as said shaftis displaced, said stem portion extending into 1 and being secured toone end of said bellows unit, the

opposite end of said bellows unit being secured in a fixed position.

3. A temperature compensated gas density relay as defined in claim 2wherein said bellows unit is located within and secured to one end of anipple and the end wall of said nipple includes an opening through whichsaid stem portion of said support member extends into said bellows unit.

4. A temperature compensated gas density relay as defined in claim 2wherein said shaft extends through said bi-metallic disc and includes anintermediate collar secured to the central portion thereof, the part ofsaid shaft below said collar extending within the hollow stem portion ofsaid support member and the part of said shaft above said collar servingto actuate said relay member.

1. In a temperature-compensated gas density relay the combinationcomprising a bellows unit subjectable to a pressurized gas to besupervised, one end of said bellows unit being fixed in position and theother end which is movable in response to a change in gas pressure beingsecured to a support member to effect a corresponding movement thereofin a direction longitudinally of the bellows unit, atemperature-compensating bi-metallic disc subjectable to the temperatureof the gas and having only the peripheral portion thereof secured tosaid support member for movement therewith, and a relay operating shaftsecured to the central portion of said bi-metallic disc which is movedin one direction to actuate a relay member such as the contacts of anelectrical switch in response to movement of said bellows unit effectedby an increase in gas pressure, said central portion of said bi-metallicdisc being spaced from said support member and said central portiontogether with said relay operating shaft secured thereto being movablein the opposite direction upon an increase in gas temperature thereby tocompensate for an increase in gas pressure resulting solely from anincrease in its temperature.
 2. A temperature compensated gas densityrelay as defined in claim 5 wherein said support member includes a headportion to which the periphery of said bimetallic disc is secured and ahollow stem portion into which a portion of said shaft extends and isguided as said shaft is displaced, said stem portion extending into andbeing secured to one end of said bellows unit, the opposite end of saidbellows unit being secured in a fixed position.
 3. A temperaturecompensated gas density relay as defined in claim 2 wherein said bellowsunit is located within and secured to one end of a nipple and the endwall of said nipple includes an opening through which said stem portionof said support member extends into said bellows unit.
 4. A temperaturecompensated gas density relay as defined in claim 2 wherein said shaftextends through said bi-metallic disc and includes an intermediatecollar secured to the central portion thereof, the part of said shaftbelow said collar extending within the hollow stem portion of saidsupport member and the part of said shaft above said collar serving toactuate said relay member.